feldspar and sodium-carbonate

The present study aimed to investigate the effects of SiO2 polymorphism on the mechanical properties of feldspathic porcelains. Seven kinds of experimental feldspathic porcelains were prepared using chemical reagents; three types of low-fusing feldspathic glasses and four types of two-phase porcelains by adding 10 or 20 mass% of fused silica (T-F) or cristobalite (T-C). Flexural strength and fracture toughness of these porcelains were evaluated. Flexural strengths of two-phase porcelains did not show any significant increase when compared with those of single-phase glasses. On the other hand, fracture toughnesses of porcelains with cristobalite showed a significant increase when compared with those of single-phase glasses. Circumferential cracks were observed in the porcelains with cristobalite. These results suggested that cristobalite could strengthen fracture toughness of feldspathic porcelains, but not flexural strength.

Topics: Aluminum Hydroxide; Aluminum Silicates; Carbonates; Crystallization; Dental Porcelain; Elasticity; Glass; Hardness; Humans; Materials Testing; Mechanics; Microscopy, Electron, Scanning; Pliability; Potassium; Potassium Compounds; Silicon Dioxide; Stress, Mechanical; Surface Properties; Thermodynamics